NEVER TOO OLD FOR AUTOIMMUNE DIABETES

A CASE REPORT OF LADA DIAGNOSED IN AN ELDERLY PATIENT

Abstract

INTRODUCTION/BACKGROUND
Latent autoimmune diabetes of adults (LADA) is characterized by slow, progressive immune-mediated destruction of pancreatic islet cells, accounting for 2-12% of diabetes in adults. It is diagnosed in individuals more than 30 years old with positive diabetes-autoantibody. Diagnosis can be challenging and sometimes delayed as these patients fit neither type 1 nor type 2 diabetes phenotypes.

CASE
We report a case of late diagnosis of LADA in a 70-year-old male who was presumed to have type 2 diabetes mellitus (T2DM) and initially presented with multiple episodes of diabetic ketoacidosis (DKA) four years ago. A 70-year-old Chinese male was diagnosed with T2DM 4 years ago and was started on treatment with metformin, vildagliptin and premixed human insulin. Despite good compliance with treatment, HbA1c remained very high (10-12%). He did not have a history of DKA, had no family history of autoimmune disease, no previous COVID infection. He was lean with a BMI of 17 kg/m2 and there were no features of insulin resistance. He presented to the hospital with severe DKA (blood sugar 26.8 mmol/L, pH 7.003, HCO3 5 mmol, ketone 7 mmol/L), attributed to atypical pneumonia. He responded to antibiotics and insulin with dextrose infusion and was subsequently discharged well with oral antidiabetic medications and basal insulin. However, after seven days, he was admitted again for severe DKA and was given intravenous steroids for adrenal insufficiency (AI). Subsequent cosyntropin tests ruled out AI. Diabetes autoantibody was requested and came back positive for anti-GAD, anti-ICA and anti-IA2. Treatment was shifted to basal-bolus insulin, resulting in improved HbA1c and no recurrence of DKA.

CONCLUSION
Diagnosis of LADA can be challenging. However, features of insulinopaenia such as DKA and the absence of clinical features of insulin resistance should raise clinical suspicion regardless of the patient’s age of presentation.